This condition is called dichogamy, which tends to ensure cross-fertilization. Pecan cultivars differ in the order that the male and female flowers mature. To ensure cross-pollination, trees of bloom Types I and II should be included in a planting. Cape Fear is a good pollinator for many other cultivars. It has adequate scab resistance but experiences severe leaf scorch in many locations.
Desirable is the cultivar most recommended in the southeastern states. Elliott is very scab-resistant. Forkert has high-quality nuts but is somewhat susceptible to scab in wet years. Gloria Grande is a highly scab-resistant cultivar. Owens possesses good tolerance to scab and other diseases. Stuart is susceptible to downy spot and moderately susceptible to scab. The following common varieties are not recommended for North Carolina because of their inability to tolerate the cold, the short growing season, or pests:.
Care of young, nonbearing trees: To get good growth, prune no more than necessary. The larger the number of leaves left to grow, the more food will be manufactured for more rapid tree growth. Strive for an average terminal growth of about 3 feet annually, by fertilizing in early March with 4 pounds of plus zinc for each inch of trunk diameter measured a foot above the soil surface.
Keep an area at least 6 feet in diameter around the tree cleanly cultivated or mulched to keep down weeds and grass. This is important because applying unnecessary fertilizer can encourage pests and disease development, which can diminish a pecan tree's ability to produce nuts.
Diseases that result in severe defoliation can also limit a pecan tree's production, says the Clemson University Extension.
These diseases include downy spot and liver spot, both of which are caused by fungi. Liver spot tends to become a problem during long periods of wet weather. Another fungal disease, powdery mildew, is unsightly but does little damage to leaves.
However, it can affect crop production if the nuts become infected early in their development. Some types of insects that feed on pecan nuts can also reduce the quality of the crop.
Healthy trees of any cultivar are better able to bear pecans consistently from year to year. For a tree to grow vigorously enough in the spring to produce the leaves and flowers it needs for a good harvest, it must carry enough assimilated food reserves over the winter to support its first flush of growth.
For that reason, anything that interferes with a tree's ability to produce and store nutrient elements, carbohydrates, etc. Among these are the nut crop itself, the age of the tree, and the tree's health. Clemson University highly recommends soil testing in order to adequately address nutrient concerns and proper soil pH.
The most reliable and commonly used tool for growers who are serious about maximizing nut production is the foliar or leaf tissue analysis. Together both soil and foliar tests provide a comprehensive approach for fertility and environmental sound nutrient management practices. They also can provide an economic benefit by not purchasing and applying unnecessary fertilizers.
This is no longer the case. In fact, improper nutrient management, whether inadequate or excessive, is now known to cause more problems than benefits in nut production.
The problem with these approaches is that excessive application of fertilizer promotes disease and insect pest issues that directly impact nut growth and development. On the other hand, the lack of proper nutrients will result in poor nut development and growth. However, in order for a grower to be absolutely sure about nutrient levels, a foliar analysis also must be conducted to identify any nutrient excesses or deficiencies.
So, the appropriate method for determining pecan tree fertility needs is to conduct both a soil and leaf-tissue analysis and to follow test recommendations for fertilizer and lime. For additional information on this visit the Clemson Agriculture Service Lab. Zinc is an essential trace element required by pecan trees for successful nut production. An early sign is a wavy margin on the leaflets. Diagnosing such zinc deficiency symptoms is difficult because disease, insect pest, and mite infestations may cause similar symptoms.
Confirmation based on a leaf tissue analysis is a standard practice in the pecan industry, and one that everyone should use. Recently, horticulturists have gained a better understanding of zinc, soil pH and other nutrient interactions. The proper method is to conduct a leaf tissue analysis as discussed. For information on leaf tissue analysis and how to collect a leaf tissue sample, please visit the Clemson Agriculture Service Lab.
This means that high yielding years will often be followed by marginally yielding years. This two or more year cycle is very common in most cultivars or varieties used today. Another contributing factor of this natural phenomenon is lack of either rainfall or irrigation water. Pecans originated in an area abundant in ground water and have a long history and need for water, especially during nut development.
Since the s all commercial producers irrigate pecans in order to insure the best possible nut quality, and to reduce the differences in nut production quantity each year. Another contributing factor is inadequate fertilization. When a tree produces a large nut crop, it utilizes a large amount of nutrients and energy.
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